Osteomyelitis in 23-Month Old Develops into DSD and Sepsis

■ Staphylococcus aureus is the most common cause of osteomyelitis and septic arthritis in children, accounting for 40% to 80% of cases.

■ Any child presenting to a primary care clinic with symptoms suspicious for osteomyelitis or septic arthritis should be referred to the nearest emergency center with pediatric expertise for management.

■ Patients with sepsis should be identified and treated quickly with fluid resuscitation; broad-spectrum empiric antibiotics; and, if needed, inotropic medications to improve outcomes in addition to appropriate surgical debridement.

■ Patients with DSD should be cared for in an ICU. Early involvement of specialty services, such as orthopedics and infectious diseases, will optimize patient outcomes.

■ With the increased incidence of community-acquired drug-resistant S aureus, a detailed history, including prior history of abscesses, is the key to early identification and treatment with the appropriate and most up-to-date recommended treatment regimen.

CASE

A 23-month-old male was brought to the pediatric emergency department with a 3-day history of fever, decreased urinary output, and right hip pain that was causing him to limp. The medical history was significant for bilateral placement of pressure-equalizing tubes 3 weeks prior to presentation. A course of unknown antibiotics was completed at that time. There was no history of known trauma. The patient's immunizations were current. His mother reported a strong family history of multiple skin abscesses that were susceptible to clindamycin. The family home was used as a day-care center for multiple children.

Physical evaluation The patient was an ill-appearing male in no acute distress. He was febrile (temperature, 101°F), tachycardic (heart rate as rapid as 120 beats per minute), and normotensive. The patient was unable to bear weight on the right leg, and he had pain with palpation and range of motion assessment of the right hip. Muscle strength was limited by pain. No rash, murmur, or skin abscess was noted. The remainder of the examination was unremarkable.

Initial diagnostic studies Results of admission laboratory studies were significant for an elevated C-reactive protein level (3.2 mg/L) and a normal WBC count. Blood samples were obtained for culture. An orthopedic specialist, who was consulted on initial presentation, recommended MRI of the right hip.

Treatment plan The clinical impression was osteomyelitis. The patient was admitted to the general pediatric floor, and blood was drawn for culture. Empiric therapy with clindamycin was started. MRI with contrast revealed changes in the right hip consistent with osteomyelitis. The patient underwent aspiration of the hip and open arthrotomy within 16 hours of admission. The initial blood culture was positive for Staphylococcus aureus within 24 hours of admission, a finding that prompted consultation with a specialist in infectious diseases, who recommended the addition of nafcillin and gentamicin to the clindamycin.

Within 30 hours of admission, the patient developed acute severe respiratory distress, with oxygen saturations of 80% requiring supplemental oxygen. A chest radiograph demonstrated acute respiratory distress syndrome (Figure 1). New, generalized pustular lesions were visible on the patient's skin. Laboratory studies revealed neutropenia with a WBC count of 2,830/µL, thrombocytopenia (platelet count, 52×103/µL), and elevations in partial thromboplastin time and prothrombin time. Elevated gamma-glutamyltransferase and conjugated bilirubin levels (66 U/L and 1.2 mg/dL, respectively) indicated liver dysfunction, and a bicarbonate level of 17 mEq/L indicated metabolic acidosis. BUN and creatinine were normal for age. Results of culture and sensitivity testing of the aspirate from the hip were positive for methicillin-susceptible S aureus (MSSA) that is resistant to clindamycin.

The patient was transferred immediately to the pediatric ICU, intubated, and placed on mechanical ventilation for hypoxemic respiratory failure. He required aggressive volume resuscitation, multiple blood products, and inotropic medications. In light of the drug resistance observed on C&S and the worsening clinical picture, clindamycin was discontinued and vancomycin was added to optimize antimicrobial coverage. Over the course of the next 6 days in the PICU, the child experienced worsening respiratory failure requiring high-frequency oscillator ventilation, and he developed liver failure and renal insufficiency. He suffered multiple complications, including a right pleural effusion and a large right pneumothorax (Figure 2) requiring thoracostomy decompression with a pigtail catheter (Figure 3). A repeat aspiration of the right hip performed at the patient's bedside produced a copious amount of purulent material, and he was taken to the OR for a second open debridement. Serial daily blood cultures continued to be positive for a total of 7 days.

Based on the patient's worsening clinical illness, continuing positive results on blood cultures, and findings suspicious of septic pulmonary emboli (PE) on radiography, MRI of the brain, spine, chest, abdomen, pelvis, and upper and lower extremities was done to evaluate for multifocal disease. Findings on MRI were consistent with septic PE; multifocal pyomyositis; osteomyelitis of the right ischium, right distal radius, and bilateral tibias; multiple small abscesses in bilateral kidneys; and a right iliac deep venous thrombosis (DVT). A hematology consult was requested.

The diagnosis was disseminated staphylococcal disease (DSD). The patient did not require further debridement of the additional infectious foci found on MRI. Management consisted of IV antimicrobials and supportive care. The right iliac DVT was treated with low molecular weight heparin.

The patient's blood cultures remained positive until day 7 of appropriate antibiotic therapy. He was weaned off supportive care, including mechanical ventilation, and inotropes over the following 2 weeks. After a 2-month hospital stay, he was discharged to an inpatient rehabilitation facility.